Method of forming bolts



which the under face of the bolt head is pro vided with a cutting edge adapted to be head, either by slipping bodily in thedies or by reason of a certain amount of flow ofithe Patented Feb. 7, 1933 UNITED STATES wewe:

STERLING H. CAMPBELL ANDFREDERIGK K. HABENIGI-IT, 0F s'i. nonrsxiurssonnr, as

SIGNORS mownsrnnn RAILWAY EQUIPMENT oomreny; onjsnnonrs; MrssoURI,

A CORPORATIUI'I OF MISSOURI Merit-ion onroniarn'e Bows :Anplication fi led li rnze, 1931. Serial 35.533350.

"Our inventionrelates to a method of forming bolts and particularly to forming bolts of the type known as self-countersinking 1n drawn into the timber to which thebolt applied." Such bolts cannot be satisfactorily produced by. the usual swaging 'operatlons dueto the difliculty of securing a sharp cut ting edge by the action] of swagin'gdies. This difficulty is increased by the tendency of thestock to move longitudinally in the holding dies during the operation of swaging the metalresulting in more or less upsetting of the shank portion of the. bolt,such longitudinal movement resulting in variationin the amount of metal forming the head with consequent imperfections in the finished prodnot.

It is the object of our invention to provide an improved method whereby bolts of the type named may be satisfactorily manufactured. ,With this object in view our invention consists, first, in providing the holdingdies with means for deforming the stock to produce a shoulder adj acent the portion from which the head is formed, thuspreventing longitudinal movement of the stock withconsequent uniformity in the amount ofmaterial in the heads; and secondly, in trimming the heads after sw'aging to secure sharp cutting edges on the under faces of the bolts.

In the accompanying drawing, which illustrates one form of apparatus by means of which our improved method may be carried 7 out, Figure l is a longitudinal section through the holding dies; Figure 2 1s a section, on an enlarged scale, taken on the line 22 of Fig ure 1; Figure 3iis'a section taken on the line 33 of F1gure 2; Figure'l 1s a cross section of the bolt, showing the underslde of the head; and Figure 5 is a longitudinalsection through the trlmming dies.

The bolts are formed from pieces of round stock 1 of stock may be cut into uniform lengths by a separate machine but we prefer to cut and grip the'stock by a singleoperation, asshown gripped in holding'dies 2. The pieces Figure the stock being severed by "the downward movementof the upper die 2,,the

lower die being stationary, in which casethe of a predeterminedlength so as to provide the l proper amount .of material for the formation of the bolt head. This is readily ".ac'corn v plished, in. the manner shown, by feeding the stock forward a uniform a distance between each stroke ofthe upper; holding die. 3 The interiorof each of the holding dies is provided', adjacent its front face, witha pair of ject inwardlybeyond the periphery of the stockyl; These faces 4, when the dies are in I closed position againstthejstock, define a prismatic space of approximatelysquare cross sectlon, and them actionis to deform the stoclg'as shown in Figure 2, forcing part of it out into the prismatic spaceand so substantially completing the formation of an angular p rtion 1 ontheshank of the bolt; Atthe same timeEthey form a shoulder adj a convex faces the'c'e'ntral parts of which'pro-' r cent the"projecting'end 1;,"which shoulder prevents any longitudinal, movement of the ,Q a

stoclcwhen" the 'swagin'g die is applied to fQrmJthe head, eXceptfsuch-slight flow of metalas takes place to complete the fill'ing oftheco'rners of'thej-angular portion 1, The amount of this is sosinall thatit does not w fhe'head. i a

' materially affect the mass- 'ofistock' available Formedin the endsiof the diesl2 an annular groove 5 of Vrshaped cross section.

The outerface of the groove is inclined'from the perpendicular with"respect' to the end,

faces of the dies ust sufllciently. to provide drawgsothat the head G 'formed by theiac tion of the swagin gdie 71will not stick in the holding dies. Theinner faceofthe groove" is inclined inthe opposite direction, and at a-greater angle so as to produce a tapered annular face on the undersideof the bolt.

head.

After. the an is swagedthe boltis re moved from the holding dies and threads 9 I e are formed thereon; The purpose of thread.-

i f ing the: bolt at this stage. of the operation rather than after completion of the head by l trimming,is to prevent injury to the cutting edge of the head by the threading mechanism.; Trimming of the head is accomplished by means of cooperating dies and 11 .Formed in the cameo or punch die 10 is a longitudinal passage 12 adapted to receive the shank ofthe boltiand is of a diameter substantially equal to. the diagonal of the angularportion 1" so that the bolt is centered in the die by Contact of thecorners of the angular portion with the wall of the passage 12. The end of the punch is'beveled to'correspond with the bevel of the face 8, and its external diameter is thatiof the finished bolt head. The intaglio die 11 .has an: internal diameter equal to the external diameter of the die 10 plus the necessary clearance and. the

J head is trimmed tocircularform, as indithe square being more or be eccentric to by dotted line more, the corner of the groove 5 cated by dotted lines A- in Figures 4' and 5, by forcing the die 11 overthe end of the die 10, The diagonals ofthe angular portion 1' may varyslightly due to the corners of less completely-filled, with the result that the bolt will be imperfectly centered and the trimming cut will the axis of the bolt as shown A in Figure 4. Further is not always "completely filled so that the effective diameter of the face8 may be somewhat less than its nominal diameter. 1 diameter of the trimming dies is substantially For thesereasons the lessthan the diameter of the face 8 so that the trimming line A will, under all condistoc a swaging die to produce a head having an inwardly tapering under face, and trimming said head to a diameter substantially less than the diameter of said face, the trimming cut intersecting the tapering face, whereby a continuous annular cutting edgeis'forme on the under side of the head.

3., The method of forming a bolt which comprises. gripping the stock between holdupsetting the projecting end by a swa'gingdie to produce aheadhaving an inwardly tapering under face, threading the bolt, andtrirnming thehead of the threaded 7 bolt to a diameter substantially less than the diameter of said tapering face, the trimming cut intersectingthe tapering face,whereby a continuous annular cutting edge is formed on the under side of the head. 5

In testimony whereof, we 7 our signatures, this 27th day of April, 1931.

STERLING H. CAMPBELL.

hereunto afiix FREDERICK K. HABENIC'HTM" tions, intersect this face and so produce an unbroken short annular cutting edge.

Having fully described our invention, what we-claim as new and desireto secure by Let tersPatent of the United States is: -I

' 1. The method of forming aself-countersinking bolt whichcomprises forging on a J length of stock a head having an annular flange with aninwardly tapering under face, and trimming the head to a diameter sub} stantially less than the diameter of said face,

i *the trimming cut intersecting the tapering face, whereby a continuous annular cutting edge is formedon the under side of the head. 2. .The method of forming a bolt which projecting jacent to the projecting, portion a comprisesgripping the stock between holdlng dies with a predetermined amount of stock projecting beyond-the dies to form a head, said dies being provided with inwardly provide a non-circular part and to form adshoulderextending beyond the peripheryofthe stock for preventing longitudinal movement of the stock, said holding dies being provided withfaces for deforming the stock to anannular groove surrounding the stock Ire? ceiving opening of the. dies and having a tapered face, upsetting the projecting end by 

